You can right click and select Compare to see the changes. Locate the customization you have added and carefully copy and paste them into your new theme.After copying your changes to the new theme, you need to upload the new theme directory to WordPress using FTP.Your FTP client will warn you that the files with the same name already exist. You need to choose Overwrite to make sure that your old theme files are replaced by new files.That’s all. You have successfully updated your WordPress theme. Visit your website to make sure that everything is working as expected.Making Theme Updates Easier by Using Child ThemesNow that you have successfully updated your theme, it is time for you to learn how to properly customize your theme. It is always a best practice to use a child theme for all your customization. Here is a step by step guide on how to create a WordPress child theme.Using a child theme makes it easier for you to update the parent theme. Your changes will remain untouched during the update, and you will not have to go through this lengthy process again. See all the pros and cons of using a WordPress child theme.We hope this article helped you update your WordPress theme without losing customization. If you come across any issues, then check out our guide on most common WordPress errors and how to fix them.If you liked this article, then please subscribe to our YouTube Channel for WordPress video tutorials. You can also find us on Twitter and Google+.